Hardware adapter

Introduction.

Multiple hardware adapters have been built and tested. The proposed
adapters currently only concern the level conversion for protocol
emulation and not the analog/SPDIF
conversion, so please check first that you have a SPDIF output on your
PC or
soundcard.

Head
unit connector.

The emulator is plugged into the CD changer connector, a 8-pin
blue "mini-iso" connector at the back of the head unit.

Where
to get it ?

This connector can be found in multiple places but make sure that
metallic contacts are provided (either pre-wired or to solder), because
the connector is sometimes proposed as an empty shell. Car hi-fi
stores are good
sources
but are sometimes expensive. eBay is another alternative and I
personally bought one from Adaptershop
(search on "blau").
If you have an actual CD Changer and you're looking for a female
connector to insert your adapter (with relay switching) between the CDC
and HU, the cheapest way I could find is to dismantle a 1.3 m extender
by Blaupunkt , ref 7 607 621 154.

Pinout

Here's a diagram of the head unit pinout. The connector we're
interested in here is the blue one: C3.Warning : This pinout is for
Philips/VDO/Dayton
"Tuner List" and "Update List" head units only. Other models (i.e.
Blaupunkt) are known to use the same physical connectors but with a
different pin assignment.

Tuner list

Update list

A

Power connector

1

Speed Dependent Volume Control

2

n/c

3

Phone mute (ground to activate)

4

+12V (constant)

5

+ Aerial (12V when radio on)

6

+ Lights (12V when lights on)

7

+ACC (12V when ACC on)

8

GND

B

Speaker connector

1

+ Rear Right

2

- Rear Right

3

+ Front Right

4

- Front Right

5

+ Front Left

6

- Front Left

7

+Rear Left

8

- Rear Left

C1

CCU(*) connector

1

DTA

2

CLK

3

MIRQ

4

n/c

5

Radio ON

6

GND

C2
(**)

AUX connector (**)

7

n/c

8

n/c

9

n/c

10

Audio Left

11

Audio Right

12

Audio GND

C3

CD Changer connector

13

Tx (from HU to
CDC or PC)

14

Rx (from PC or
CDC to HU)

15

GND

16

12V (constant)

17

HU ON (12V when
HU is ON)

18

SPDIF IN (***)

19

SPDIF GND (***)

20

(SPDIF GND)
(***)

(*) Central Communication Unit. This is the way the HU receives stalk
control commands and sends information to the dash display.
(**) Auxiliary input only available on Update List models.
The AUX input must be activated in the head unit's menu. C2 doesn't
exist at all on Tuner
List models
(***) Models before 2000 have an analog CD Changer audio input instead
of SPDIF. In that case, the pinout is as follows: 18=Audio GND,
19=Audio Left and 20=Audio Right.

Sample
circuits.

Note that multiple functions can be provided by following circuits. Not all
circuits provide all functions, but you can probably easily combine
different circuits if needed.
These functions are :
- level adaptation in both directions : Mandatory.
- optical isolation between PC and head-unit : Optional or mandatory... depends on your PC and HU
- propagation of "remote out" signal from the HU to the PC (this wire
is at 12V once HU is on and triggers "booting" of actual CD changers) :
Optional.
- control of relays to switch back and forth between PC and actual CD
Changer (if you have one) with the RTS signal : Optional (not done yet).

Original
MAX3232-based version

For maximal RS232 compatibility, the first version used uses a MAX3232
to provide the correct levels to the PC.
It has been built multiple times and works as long as the following
condition is fulfilled :Warning : this version of the adapter assumes
HU ground
and PC ground are shared, which is frequently not the case with
inverter-powered PCs. Please check if it's the case for you. You might
also run into ground loop noise.

Opto-isolated
version

For optical isolation between PC and HU, here is a
version using optocouplers. Please note that it relies on fixed levels
provided on the RTS (+) and DTR (-) pins of the serial port. Latest
versions of the software
emulators provided here take care of this. HU_ON (aka HU_REMOTE) is
transmitted to the PC, but note that latest software versions don't
need it and determine if HU is on simply by checking they get reply to
the requests.

Simplest
version

For maximum simplicity, here is a version without a single IC, only 2
transistors and a few passive components. It might or might not work
depending on the thresholds of your PC's serial port.Warning : this version of the adapter assumes
HU ground
and PC ground are shared, which is frequently not the case with
inverter-powered PCs. Please check if it's the case for you. You might
also run into ground loop noise.

Full version

This version is inspired by the opto-coupled one above with
slightly different parts. It also features a relay switching and is
particularly suited if you have an actual CD changer in your car : if
the carPC is off or the emulator is not running, the hardware emulator
is disconnected and connection to the actual CDC is active, providing
among other things a smooth transition when booting or shutting down.